1. Field of the Invention
The present invention relates to a radiation-sensitive resin composition, and particularly to a radiation-sensitive resin composition which can be favorably used as a chemically amplified photoresist useful in micro-processing using various radiations, e.g., far-ultraviolet radiation such as KrF excimer laser or ArF excimer laser, X rays such as synchrotron radiation, charged particle radiation such as electron beam, etc.
2. Description of the Prior Art
In the field of micro-processing represented by. fabrication of integrated circuit elemental devices, to realize a higher degree of integration, lithography technology capable of micro-processing on the order of sub-half micron (0.25 xcexcm or less) is recently under development, and it is expected that micro-processing on the order of sub-quarter micron (0.25 xcexcm or less) will be required in the near future.
In the conventional lithography processing, near ultra-violet radiation such as i-line and the like are used as radiation. However, it is said to be extremely difficult to realize micro-processing on the order of sub-quarter micron with near ultra-violet radiation.
Thus, to enable micro-processing on the order of sub-quarter micron, the use of radiations with shorter wave lengths is considered. Radiations having such short wave lengths include, for example, a bright line spectrum of mercury lamps, far-ultraviolet radiations represented by excimer lasers, X rays, electron beam, etc. Out of these, KrF excimer laser or ArF excimer laser attracts particular attention.
As a radiation-sensitive resin composition suited for irradiation with excimer lasers, there have been proposed many compositions (hereinafter, referred to as xe2x80x9cchemically amplified radiation-sensitive compositionxe2x80x9d) using chemical amplification action effected by a component containing an acid-cleavable functional group and a component which generates an acid upon irradiation with radiation (hereinafter, referred to as xe2x80x9cacid-generating agentxe2x80x9d).
For example, Japanese Patent Publication (kokoku) No. 2-27660 discloses, as one of the chemically amplified radiation-sensitive compositions, a composition comprising a polymer having a t-butyl ester group of a carboxylic acid or a t-butyl carbonate group of a phenol, and an acid-generating agent. This composition uses the phenomenon that the t-butyl ester group or the t-butyl carbonate group present in the polymer cleaves by the catalytic action of an acid generated by irradiation, so that the polymer comes to have acidic groups of carboxyl or phenol group, and the irradiated areas of the photoresist film thereby become readily soluble in alkaline developing solution.
Most of the chemically amplified radiation-sensitive compositions known heretofore, are based on a phenolic resin. The phenolic resin has a drawback that when far ultraviolet radiation is used as radiation, the far ultraviolet radiation is absorbed by aromatic rings in the resin, and therefore the far ultraviolet radiation can not reach the lower portion near the substrate of the photoresist film sufficiently. For this, irradiation dose is larger at the upper portion of the photoresist film but on the other hand it is smaller at the lower portion, resulting in the problem that the photoresist pattern after development forms a tapered resist profile, that is, the width is smaller at the upper portion and become larger at the lower portion. This means that sufficient resolution can not be obtained. It is also a problem that if the developed photoresist pattern is tapered, desired dimensional accuracy can not be achieved at subsequent steps, i.e., at the steps of etching, ion implantation, etc. Furthermore, if the upper portion of the photoresist pattern in section is not rectangular, the rate of loss of the photoresist caused by dry etching is increased, so that the etching conditions can be controlled with difficulty.
The shape of a photoresist pattern in section can be improved by increasing the transmittance of the photoresist film with respect to radiation. For example, since (meth)acrylate resins represented by polymethyl methacrylate have a high transparency with respect to far ultraviolet radiation, they are very favorable resins from the viewpoint of transmittance of radiation. For example, Japanese Laid-open Patent Publication (kokai) No. 4-226461 discloses a chemically amplified radiation-sensitive resin composition using a methacrylate resin. Although this composition is excellent in performance of micro-processing, it has a drawback of poor dry etching resistance because it contains no aromatic rings. Also, in this case, etching processing with high accuracy can be conducted with difficulty.
It is an object of the present invention to provide a radiation-sensitive resin composition which is particularly excellent in transparency with respect to radiation and dry etching resistance and which can give a photoresist pattern excellent in adhesion to substrates, sensitivity, resolution, developability, etc., as a chemically amplified photoresist sensitive to activated radiations, for example, far ultraviolet radiation represented by KrF excimer laser or Arf excimer laser.
The present invention provides a radiation-sensitive resin composition comprising (A) a resin containing an alicyclic skeleton in the backbone, and (B) a radiation-sensitive acid-generating agent capable of generating an acid upon irradiation.
The radiation-sensitive resin composition of the present invention is, as a chemically amplified photoresist, excellent particularly in transparency for radiation and dry etching resistance, and can form a photoresist pattern excellent in adhesion to substrates, sensitivity, resolution and developability. The composition can be very suitably used in the production of semiconductor devices of which miniaturization will further proceed in the future.
The following terms are herein used to generically have the meaning below.
The term xe2x80x9c(cyclo)alkanexe2x80x9d includes alkane and cycloalkane, xe2x80x9c(cyclo)alkylxe2x80x9d includes alkyl and cycloalkyl, xe2x80x9c(cyclo)alkoxyxe2x80x9d includes alkoxy and cycloalkoxy, and xe2x80x9c(cyclo)acylxe2x80x9d includes acyl and cycloalkylcarbonyl.
The term xe2x80x9c(meth)acrylic acidxe2x80x9d includes acrylic acid and methacrylic acid, and xe2x80x9c(meth)acrylatexe2x80x9d includes acrylate and methacrylate.
The term xe2x80x9c(co)polymerxe2x80x9d includes homopolymer and copolymer, and xe2x80x9c(co)polymerizationxe2x80x9d includes homopolymerization and copolymerization.
The present invention will now be described in detail.
Resin (A)
The alicyclic skeleton contained in the resin comprising an alicyclic skeleton in the backbone (hereinafter, referred to as xe2x80x9cresin (A)xe2x80x9d) may be monocyclic as in the skeletons derived from cycloalkanes or polycyclic as in the skeletons derived from bicyclo[2.2.1]heptane, tetracyclo[4.4.0.12,5.17,10]dodecane or the like. The resin (A) may contain one or more kinds of alicyclic skeletons.
Said alicyclic skeleton may contain at least one group which is cleaved by an acid (hereinafter, referred to as xe2x80x9cacid-cleavable groupxe2x80x9d) at any position thereon. The alicyclic skeleton may optionally contain one or more substituents other than the acid-cleavable group, e.g., a halogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, a monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms at any position thereon.
The use of the resin (A) comprising an alicyclic skeleton in the backbone according to the present invention, has been able to provide a radiation-sensitive resin composition which is particularly excellent in transparency with respect to radiation and dry etching resistance, and which can give a photoresist pattern excellent in adhesion to substrates, sensitivity, resolution, developability, etc., as a photoresist.
The resin (A) used in the present invention is preferably a resin which is insoluble or slightly soluble in alkali in itself but which has at least one acid-cleavable group to be cleaved by the catalytic action of an acid and becomes alkali-soluble. The terminology xe2x80x9cinsoluble or slightly soluble in alkalixe2x80x9d herein means that the resin is insoluble or slightly soluble in a developing solution of an alkaline solution used for development of the photoresist film formed from the radiation-sensitive resin composition of the present invention. The solubility of the resin (A) in alkali can be regulated by the content of acidic functional groups such as carboxyl groups.
Preferred alicyclic skeletons in the resin (A) include the skeleton represented by the following general formula (1) and the skeleton represented by the general formula (2), and the skeleton of the general formula (1) is particularly preferred. 
wherein in the general formula (1) and general formula (2), n is 0 or 1, A and B represent independently a hydrogen atom, a halogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms or a monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms, and X and Y represent independently a hydrogen atom, a halogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, a monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms or an acid-cleavable group, provided that at least one of X and Y is an acid-cleavable group.
Preferably, the acid-cleavable group of X and Y in the general formula (1) and general formula (2) is a group: xe2x80x94(CH2)iCOOR1, xe2x80x94(CH2)iOCOR2 or xe2x80x94(CH2)iCN wherein R1 is a hydrocarbon group having 1 to 10 carbon atoms, a halogenated hydrocarbon group having 1 to 10 carbon atoms, a tetrahydrofuranyl group, a tetrahydropyranyl group, a carbobutoxymethyl group, a carbobutoxyethyl group, a carbobutoxypropyl group or a trialkylsilyl group the alkyl groups of which each have 1 to 4 carbon atoms, R2 represents a hydrocarbon group having 1 to 10 carbon atoms or a halogenated hydrocarbon group having 1 to 10 carbon atoms, and i is an integer of 0 to 4; or X and Y are bonded to each other to form a bivalent group represented by the formula: 
wherein Z is xe2x80x94Oxe2x80x94 or xe2x80x94N(R3)xe2x80x94 in which R3 is a hydrogen atom, a halogen atom, an alkyl group having 1 to 8 carbon atoms or a xe2x80x94SO2R4 group having 1 to 4 carbon atoms in which R4 is an alkyl group having 1 to 4 carbon atoms or a halogenated alkyl group having 1 to 4 carbon atoms, or the formula: xe2x80x94Oxe2x80x94, so that X and Y form, jointly with the two carbon atoms which constitute a part of the alicyclic skeleton and to which X and Y are directly bonded, an oxygen-containing or nitrogen-containing heterocyclic structure having the formula: 
where Z is as defined above.
In the preferable acid-cleavable groups of X and Y in the general formula (1) and general formula (2), the group xe2x80x94(CH2)iCOOR1 includes, for example, (cyclo)alkoxycarbonyl groups such as methoxycarbonyl, ethoxycarbonyl, n-propoxycarbonyl, isopropoxycarbonyl, n-butoxycarbonyl, 2-methylpropoxycarbonyl, 1-methylpropoxycarbonyl, t-butoxycarbonyl, n-pentyloxycarbonyl, n-hexyloxycarbonyl, n-heptyloxycarbonyl, n-octyloxycarbonyl, n-decyloxycarbonyl, cyclopentyloxycarbonyl, cyclohexyloxycarbonyl, 4-t-butylcyclohexyloxycarbonyl, cycloheptyloxycarbonyl, and cyclooctyloxycarbonyl groups; aryloxycarbonyl groups such as phenoxycarbonyl, 4-t-butylphenoxycarbonyl, and 1-naphthyloxycarbonyl groups; aralkyloxycarbonyl groups such as benzyloxycarbonyl, and 4-t-butylbenzyloxycarbonyl groups; (cyclo)alkoxycarbonylmethyl groups such as methoxycarbonylmethyl, ethoxycarbonylmethyl, n-propoxycarbonylmethyl, isopropoxycarbonylmethyl, n-butoxycarbonylmethyl, 2-methylpropoxycarbonylmethyl, 1-methylpropoxycarbonylmethyl, t-butoxycarbonylmethyl, cyclohexyloxycarbonylmethyl and 4-t-butylcyclohexyloxycarbonylmethyl groups; aryloxycarbonylmethyl groups such as phenoxycarbonylmethyl and 1-naphthyloxycarbonylmethyl groups; aralkyloxycarbonylmethyl groups such as benzyloxycarbonylmethyl and 4-t-butylbenzyloxycarbonylmethyl groups; (cyclo)alkoxycarbonylethyl groups such as 2-methoxycarbonylethyl, 2-ethoxycarbonylethyl, 2-n-propoxycarbonylethyl, 2-isopropoxycarbonylethyl, 2-n-butoxycarbonylethyl, 2-(2-methylpropoxy)carbonylethyl, 2-(1-methylpropoxy)carbonylethyl, 2-t-butoxycarbonylethyl, 2-cyclohexyloxycarbonylethyl and 2-(4-butylcyclohexyloxycarbonyl)ethyl groups; 2-aryloxycarbonylethyl groups such as 2-phenoxycarbonylethyl and 2-(1-naphthylcarbonyl)ethyl groups; and 2-aralkyloxycarbonylethyl groups such as 2-benzyloxycarbonylethyl and 2-(4-t-butylbenzyloxycarbonyl)ethyl groups.
Among these groups, preferred are groups corresponding to the group xe2x80x94COOR1, more preferred are (cyclo)alkoxycarbonyl groups, and particularly preferred are methoxycarbonyl, ethoxycarbonyl, n-butoxycarbonyl, t-butoxycarbonyl and cyclohexyloxycarbonyl groups.
The group xe2x80x94(CH2)iOCOR2 includes, for example, a (cyclo)acyloxy group such as acetyloxy, propionyloxy, butyryloxy, valeryloxy, caproyloxy, heptanoyloxy, octanoyloxy, nonanoyloxy, decanoyloxy, undecanoyloxy, cyclohexylcarbonyloxy and 4-t-butylcyclohexylcarbonyloxy; an arylcarbonyloxy group such as benzoyloxy, 4-t-butylbenzoyloxy and 1-naphthoyloxy groups; an aralkylcarbonyloxy group such as benzylcarbonyloxy and 4-t-benzylcarbonyloxy; a (cyclo)acyloxymethyl group such as acetyloxycarbonylmethyl, propionyloxycarbonylmethyl, butylyloxycarbonylmethyl, cyclohexylcarbonyloxymethyl and 4-t-butylcyclohexylcarbonyloxymethyl groups; an arylcarbonyloxymethyl group such as benzoyloxymethyl and 1-naphthoyloxymethyl; an aralkylcarbonyloxymethyl group such as benzylcarbonyloxymethyl and 4-t-butylbenzylcarbonyloxymethyl groups; a 2-(cyclo)acyloxyethyl group such as 2-acetyloxyethyl, 2-propionyloxyethyl, 2-butylyloxyethyl, 2-cyclohexylcarbonyloxyethyl and 2-(4-t-butylcyclohexylcarbonyloxy)ethyl groups; a 2-arylcarbonyloxyethyl group such as 2-benzoyloxyethyl and 2-(1-naphthoyloxy)ethyl groups; and 2-aralkylcarbonyloxyethyl group such as 2-benzylcarbonyloxyethyl and 2-(4-t-butylbenzylcarbonyloxy)ethyl groups.
The group xe2x80x94(CH2)iCN includes, for example, cyano, cyanomethyl, 2-cyanoethyl, 2-cyanopropyl, 3-cyanopropyl and 4-cyanobutyl groups.
Further, the halogen atom of A, B, X and Y in the general formulas (1) and general formula (2) includes, for example, F, Cl, Br and I. The monovalent hydrocarbon group having 1 to 10 carbon atoms of A, B, X and Y includes, for example, a (cyclo)alkyl group such as methyl, ethyl, n-propyl, isopropyl, n-butyl, 2-methylpropyl, 1-methylpropyl, t-butyl, n-hexyl, n-octyl, n-decyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl groups; an aryl group such as phenyl, 4-t-butylphenyl and 1-naphthyl groups; and an aralkyl group such as benzyl and 4-t-butylbenzyl groups. The monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms of A, B, X and Y includes, for example, halogenated derivatives of said monovalent hydrocarbon group having 1 to 10 carbon atoms.
In the resin (A), at least one alicyclic skeleton represented by the general formula (1) and at least one alicyclic skeleton represented by the general formula (2) can be independently present and the alicyclic skeleton represented by the general formula (1) and the alicyclic skeleton represented by the general formula (2) can be present together.
The resin (A) having an alicyclic skeleton selected from the group consisting of the alicyclic skeleton represented by the general formula (1) and the alicyclic skeleton represented by general formula (2), in the backbone [hereinafter, referred to as xe2x80x9cresin (AI)xe2x80x9d] can be produced by, for example, the following methods (a) to (e):
(a) A method comprising the step of ring-opening polymerizing or copolymerizing at least one norbornene derivative represented by the following general formula (7) [hereinafter, referred to as xe2x80x9cnorbornene derivative (a)xe2x80x9d] and optionally at least one other ring-opening copolymerizable unsaturated alicyclic compound. 
wherein in the general formula (7), n, A, B, X and Y each have the same meaning as in the general formula (1) and general formula (2), R5, R6, R7 and R8 represent independently a hydrogen atom, a halogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms or a monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms.
(b) A method comprising radical copolymerizing at least one norbornene derivative (a) and at least one copolymerizable unsaturated compound such as ethylene or maleic acid anhydride.
(c) A method comprising partially hydrolyzing and/or solvolyzing a resin obtained by said method (a) or (b) in accordance with a conventional procedure.
(d) A method comprising newly incorporating a group of xe2x80x94COOR1 or xe2x80x94OCOR2 (hereinafter, these groups being together generically referred to as xe2x80x9cacid-cleavable ester groupxe2x80x9d) into the resin obtained by said method (c) by at least partially esterifying the carboxyl groups or hydroxyl groups contained in said resin in accordance with a conventional procedure.
(e) A method comprising the step of ring-opening (co)polymerizing or radical copolymerizing at least one norbornene derivative [hereinafter, referred to as xe2x80x9cnorbornene derivative (b)xe2x80x9d] represented by the following general formula (8) and at least partially esterifying the carboxyl groups or hydroxyl groups contained in the resulting (co)polymer in accordance with a conventional procedure to introduce an acid-cleavable ester group into the (co)polymer. 
wherein in the general formula (8), n, A and B each have the same meaning as in the general formula (1) and general formula (2), R5, R6, R7 and R8 each have the same meaning as in the general formula (7), C and D represent independently a hydrogen atom, a halogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, a monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms, xe2x80x94(CH2)iCOOH or xe2x80x94(CH2)iOH wherein i has the same meaning as the i in the acid-cleavable group defined in the general formula (1) and general formula (2), provided that at least one of C and D represents xe2x80x94(CH2)iCOOH or xe2x80x94(CH2)iOH.
Additionally, the resin obtained by said method (c), (d) or (e) can be modified by, for example, the following method (f):
(f) A method comprising incorporating other acid-cleavable group into said resin by further esterifying a carboxyl group or hydroxyl group contained in the resin.
The methods (a) to (f) are now described in order.
First, in said method (a), the halogen atom, the monovalent hydrocarbon group having 1 to 10 carbon atoms and the monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms, of R5, R6, R7 and R8 in the general formula (7) include, for example, the same groups as those exemplified for said general formula (1) and general formula (2).
Among the norbornene derivatives (a), specific examples of the compound represented by the general formula (7) where n is 0 include:
5-methoxycarbonylbicyclo[2.2.1]hept-2-ene,
5-ethoxycarbonylbicyclo[2.2.1]hept-2-ene,
5-n-propoxycarbonylbicyclo[2.2.1]hept-2-ene,
5-isopropoxycarbonylbicyclo[2.2.1]hept-2-ene,
5-n-butoxycarbonylbicyclo[2.2.1]hept-2-ene,
5-(2-methylpropoxy)carbonylbicyclo[2.2.1]hept-2-ene,
5-(1-methylpropoxy)carbonylbicyclo[2.2.1]hept-2-ene,
5-t-butoxycarbonylbicyclo[2.2.1]hept-2-ene,
5-cyclohexyloxycarbonylbicyclo[2.2.1]hept-2-ene,
5-(4xe2x80x2-t-butylcyclohexyloxy)carbonylbicyclo[2.2.1]hept-2-ene,
5-phenoxycarbonylbicyclo[2.2.1]hept-2-ene,
5-tetrahydrofuranyloxycarbonylbicyclo[2.2.1]hept-2-ene,
5-tetrahydropyranyloxycarbonylbicyclo[2.2.1]hept-2-ene,
5-acetyloxybicyclo[2.2.1]hept-2-ene,
5-cyanobicyclo[2.2.1]hept-2-ene,
5-methyl-5-methoxycarbonylbicyclo[2.2.1]hept-2-ene,
5-methyl-5-ethoxycarbonylbicyclo[2.2.1]hept-2-ene,
5-methyl-5-n-propoxycarbonylbicyclo[2.2.1]hept-2-ene,
5-methyl-5-isopropoxycarbonylbicyclo[2.2.1]hept-2-ene,
5-methyl-5-n-butoxycarbonylbicyclo[2.2.1]hept-2-ene,
5-methyl-5-(2-methylpropoxy)carbonylbicyclo[2.2.1]hept-2-ene,
5-methyl-5-(1-methylpropoxy)carbonylbicyclo[2.2.1]hept-2-ene,
5-methyl-5-t-butoxycarbonylbicyclo[2.2.1]hept-2-ene,
5-methyl-5-cyclohexyloxycarbonylbicyclo[2.2.1]hept-2-ene,
5-methyl-5-(4xe2x80x2-t-butylcyclohexyloxy)carbonylbicyclo[2.2.1]hept-2-ene,
5-methyl-5-phenoxycarbonylbicyclo[2.2.1]hept-2-ene,
5-methyl-5-tetrahydrofuranyloxycarbonylbicyclo[2.2.1]hept-2-ene,
5-methyl-5-tetrahydropyranyloxycarbonylbicyclo[2.2.1]hept-2-ene,
5-methyl-5-acetyloxybicyclo[2.2.1]hept-2-ene,
5-methyl-5-cyanobicyclo[2.2.1]hept-2-ene,
5,6-di(methoxycarbonyl)bicyclo[2.2.1]hept-2-ene
5,6-di(ethoxycarbonyl)bicyclo[2.2.1]hept-2-ene,
5,6-di(n-propoxycarbonyl)bicyclo[2.2.1]hept-2-ene,
5,6-di(isopropoxycarbonyl)bicyclo[2.2.1]hept-2-ene,
5,6-di(n-butoxycarbonyl)bicyclo[2.2.1]hept-2-ene,
5,6-di(t-butoxycarbonyl)bicyclo[2.2.1]hept-2-ene,
5,6-di(phenoxycarbonyl)bicyclo[2.2.1]hept-2-ene,
5,6-di(tetrahydrofuranyloxycarbonyl)bicyclo[2.2.1]hept-2-ene,
5,6-di(tetrahydropyranyloxycarbonyl)bicyclo[2.2.1]hept-2-ene, and
5,6-dicarboxyanhydridebicyclo[2.2.1]hept-2-ene.
Among the norbornene derivatives (a), specific examples of the compound represented by the general formula (7) where n is 1 include:
8-methoxycarbonyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-ethoxycarbonyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-n-propoxycarbonyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-isopropoxycarbonyltetracyclo[4.4.0.12,51.17,10]dodec-3-ene,
8-n-butoxycarbonyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-(2-methylpropoxy)carbonyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-(1-methylpropoxy)carbonyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-t-butoxycarbonyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-cyclohexyloxycarbonyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-(4xe2x80x2-t-butylcyclohexyloxy)carbonyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-phenoxycarbonyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-tetrahydrofuranyloxycarbonyltetracyclo[4.4.0.12,5.17,10]-3-dodecene,
8-tetrahydropyranyloxycarbonyltetracyclo[4.4.0.12,5.17,10]-3-dodecene,
8-acetyloxytetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-cyanotracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-methyl-8-methoxycarbonyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-methyl-8-ethoxycarbonyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-methyl-8-n-propoxycarbonyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-methyl-8-isopropoxycarbonyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-methyl-8-n-butoxycarbonyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-methyl-8-(2-methylpropoxy)carbonyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-methyl-8-(1-methylpropoxy)carbonyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-methyl-8-t-butoxycarbonyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-methyl-8-cyclohexyloxycarbonyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-methyl-8-(4xe2x80x2-t-butylcyclohexyloxy)carbonyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-methyl-8-phenoxycarbonyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-methyl-8-tetrahydrofuranyloxycarbonyltetracyclo[4.4.0.12,5.17,10]dodecene,
8-methyl-8-tetrahydropyranyloxycarbonyltetracyclo[4.4.0.12,5.17,10]-3-dodecene,
8-methyl-8-acetyloxytetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-methyl-8-cyanotetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,9-di(methoxycarbonyl)tetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,9-di(ethoxycarbonyl)tetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,9-di(n-propoxycarbonyl)tetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,9-di(isopropoxycarbonyl)tetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,9-di(n-butoxycarbonyl)tetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,9-di(t-butoxycarbonyl)tetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,9-di(cyclohexyloxycarbonyl)tetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,9-di(phenoxycarbonyl)tetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,9-di(tetrahydrofuranyloxycarbonyl)tetracyclo[4.4.0.12,5.17,10]3-dodecene, 8,9-di(tetrahydropyranyloxycarbonyl)tetracyclo[4.4.0.12,5.17,10]-3-dodecene, and
8,9-dicarboxyanhydridetetracyclo[4.4.0.12,5.17,10]dodec-3-ene.
In the present invention, when two or more of said norbornene derivatives (a) are mixed for use, it is preferred that the compound represented by the general formula (7) where n is 0 and the compound represented by the same formula where n is 1 are used in combination.
Specific examples of the other unsaturated alicyclic compounds capable of ring-opening copolymerizing with the norbornene derivatives (a) include:
bicyclo[2.2.1]hept-2-ene,
bicyclo[2.2.1]hept-2-ene-5-carboxylic acid,
5-methylbicyclo[2.2.1]hept-2-ene-5-carboxylic acid,
5-methylbicyclo[2.2.1]hept-2-ene,
5-ethylbicyclo[2.2.1]hept-2-ene,
tetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
tetracyclo[4.4.0.12,5.17,10]dodec-3-ene-8-carboxylic acid,
8-methyltetracyclo[4.4.0.12,5.117,10]dodec-3-ene-8-carboxylic acid,
8-methyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-ethyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-fluorotetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-fluoromethyltetracyclo[4.4.0.12,5. 17,10]dodec-3-ene,
8-difluoromethyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-trifluoromethyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene
8-pentafluoroethyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,8-difluorotetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,9-difluorotetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,8-bis(trifluoromethyl)tetracyclo[4.4.0.12,5. 17,10]dodec-3-ene,
8,9-bis(trifluoromethyl)tetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-methyl-8-trifluoromethyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,8,9-trifluorotetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,8,9-tris(trifluoromethyl)tetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,8,9,9-tetrafluorotetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,8,9,9-tetrakis(trifluoromethyl)tetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,8-difluoro-9,9-bis(trifluoromethyl)tetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,9-difluoro-8,9-bis(trifluoromethyl)tetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,8,9-trifluoro-9-trifluoromethyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,8,9-trifluoro-9-trifluoromethoxytetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,8,9-trifluoro-9-pentafluoropropoxytetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-fluoro-8-pentafluoroethyl-9,9-bis(trifluoromethyl)tetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,9-difluoro-8-heptafluoroisopropyl-9-trifluoromethyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-chloro-8,9,9-trifluorotetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8,9-dichloro-8,9-bis(trifluoromethyl)tetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-(2,2,2-trifluorocarboxyethyl)tetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
8-methyl-8-(2,2,2-trifluorocarboxyethyl)tetracyclo[4.4.0.12,5.17,10]dodec-3-ene,
cyclobutene, cyclopentene, cyclooctene, 1,5-cyclooctadiene, 1,5,9-cyclododecatriene, norbornene, 5-ethylidenenorbornene, 5-methylnorbornene, dicyclopentadiene,
tricyclo[5.2.1.02,6]deca-8-ene, tricyclo[5.2.1.02,6]deca-3-ene, tricyclo[4.4.0.12,5]undeca-3-ene,
tricyclo[6.2.1.01,8]undeca-9-ene, tricyclo[6.2.1.01,8]undeca-4-ene, tetracyclo[4.4.0.12,5.17,10.01,6]dodec-3-ene, 8-methyltetracyclo[4.4.0.12,5.17,10.01,6]dodec-3-ene, 8-ethylidenetetracyclo[4.4.0.12,5.12,5.17,10.17,12]dodec-3-ene, 8-ethylidenetetracyclo[4.4.0.12,5.17,10.01,6]dodec-3-ene,
pentacyclo[6.5.1.13,6.02,7.09,13]pentadeca-4-ene, and
pentacyclo[7.4.0.12,5.19,12.08,13]pentadeca-3-ene.
In the resin (AI), the content of the structural units derived from said other unsaturated alicyclic compound is generally 50 mole % or less, preferably 40 mole % or less, and more preferably 30 mole % or less, based on the total structural units contained in the resin (AI). If the content of the structural units derived from the other unsaturated alicyclic compound is more than 50 mole %, dry etching resistance may tend to lower.
The ring-opening (co)polymerization in the method (a) can be carried out, for example, using a metathesis catalyst in a suitable solvent.
The metathesis catalyst is comprised of generally a combination of at least one compound selected from the group consisting of W, Mo and Re compounds (hereinafter, referred to as xe2x80x9cspecified transition metal compoundxe2x80x9d) with at least one compound, selected from the group consisting of the compounds of the metals of Group IA, IIA, IIIA, IVA and IVB in the Deming""s periodic table, the compounds having metal-carbon bonding and/or metal-hydrogen bonding (hereinafter, referred to as xe2x80x9cspecified organometallic compoundxe2x80x9d).
The specified transition metal compound includes, for example, halides, oxyhalides, alkoxyhalides, alkoxides, carboxylic acid salts, (oxy)acetylacetonates, carbonyl complexes, acetonitrile complexes, hydride complexes, and their derivatives. Among these compounds, preferred are W compounds or Mo compounds, more specifically halides, oxyhalides or alkoxyhalides of W or of Mo, from the viewpoint of polymerization activity, practical use, etc.
The specified transition metal compound may be a compound coordinated with a suitable complexing agent such as triphenylphosphine (P(C6H5)3) and pyridine (NC5H5).
Specific examples of the specified transition metal compound include WCl6, WCl5, WCl4, WBr6, WF6, WI6, MoCl5, MoCl4, MoCl3, ReCl3, WOCl4, WOCl3, WOBr3, MoOCl3, MoOBr3, ReOCl3, ReOBr3, WCl2(OC2H5)4, W(OC2H5)6, MoCl3(OC2H5)2, Mo(OC2H5)5, WO2(acac)2 wherein acac stands for an acetylacetonate radical, MoO2(acac)2, W(OCOR)5 wherein OCOR stands for a carboxylic acid radical, Mo(OCOR)5, W(CO)6, Mo(CO)6, Re2(CO)10, WCl5.P(C6H5)3, MoCl5.P(C6H5)3, ReOBr3.P(C6H5)3, WCl6.NC5H5, W(CO)5.P(C6H5)3, and W(CO)3.(CH3CN)3.
Among them, particularly preferred are WCl6, MoCl5, WCl2(OC2H5)4 and MOCl3(OC2H5)2.
Said specified transition metal compound can be used singly or in a combination of two or more thereof.
The specified transition metal compound component constituting a metathesis catalyst can be also used as a mixture of two or more compounds reacting in a polymerization system to form the specified transition metal compound.
Specific examples of the specified organometallic compound include n-C4H9Li, n-C5H11Na, n-C6H5Na, CH3MgI, C2H5MgBr, CH3MgBr, n-C3H7MgCl, t-C4H9MgCl, CH2xe2x95x90CHCH2MgCl, (C2H5)2Zn, (C2H5)2Cd, CaZn(C2H5)4, (CH3)3B, (C2H5)3B, (n-C4H9)3B, (CH3)3Al, (CH3)2AlCl, CH3AlCl2, (CH3)3Al2Cl3, (C2H5)3Al, (C2H5)3Al2Cl3, (C2H5)2Al.O(C2H5)2, (C2H5)2AlCl, C2H5AlCl2, (C2H5)2AlH, (C2H5)2AlOC2H5, (C2H5)2AlCN, LiAl(C2H5)2, (n-C3H7)3Al, (i-C4H9)3Al, (i-C4H9)2AlH, (n-C6H13)3Al, (n-C8H17)3Al, (C6H5)3Al, (CH3)4Ga, (CH3)4Sn, (n-C4H9)4Sn, (C2H5)3SnH, LiH, NaH, B2H6, NaBH4, AlH3, LiAlH4 and TiH4.
Among these compounds, preferred are (CH3)3Al, (CH3)2AlCl, CH3AlCl2, (CH3)3Al2Cl3, (C2H5)3Al, (C2H5)2AlCl, C2H5AlCl2, (C2H5)3Al2Cl3, (C2H5)2AlH, (C2H5)2AlOC2H5, (C2H5)2AlCN, (n-C3H7)3Al, (i-C4H9)3Al, (i-C4H9)2AlH, (n-C6H13)3Al, (n-C8H17)3Al, and (C6H5)3Al.
Said specified organometallic compound can be used singly or in a combination of two or more thereof.
With regard to the quantitative relation between the specified transition metal compound and the specified organometallic compound, the specified transition metal compound/the specified organometallic compound is in the range of generally from 1/1 to 1/100, and preferably from 1/2 to 1/50, in terms of metal atomic ratio.
In order to enhance catalytic activity, one or more of the following activating agents {circle around (1)} to {circle around (9)} can be added to said catalyst consisting of a combination of said specified transition metal compound and said specified organometallic compound.
Activating Agent {circle around (1)}:
Boron compounds such as B, BF3, BCl3, B(O-n-C4H9)3, BF3.O(CH3)2, BF3.O(C2H5)2, BF3.O(n-C4H9)2, BF3.2C6H5OH, BF3.2CH3COOH, BF3.CO(NH2)2, BF3.N(C2H4OH)3, BF3.piperidine, BF3.NH2C2H5, B2O3 and H3BO3; and silicon compounds such as Si(OC2H5)4 and SiCl4.
Activating Agent {circle around (2)}:
Alcohols, hydroperoxides, dialkylperoxides and diecylperoxides.
Activating Agent {circle around (3)}:
Water
Activating Agent {circle around (4)}:
Oxygen
Activating Agent {circle around (5)}:
Carbonyl compounds such as aldehydes and ketones; and their oligomers or polymers.
Activating Agent {circle around (6)}:
Cyclic ethers such as ethylene oxide, epichlorohydrin and oxetane.
Activating Agent {circle around (7)}:
Amides such as N,N-dimethylformamide and N,N-dimethylacetamide; amines such as aniline, morpholine and piperidine; and azo compounds such as azobenzene.
Activating Agent {circle around (8)}:
N-Nitroso compounds such as N-nitrosodimethylamine and N-nitrosodiphenylamine.
Activating Agent {circle around (9)}:
Compounds having nitrogen-chlorine bonding or sulfur-chlorine bonding, such as trichloromelamine, N-chlorosuccinimide and phenylsulfenyl chloride.
The quantitative relation between these activating agents and the specified transition metal compound can not be unconditionally determined since the relation changes in a very wide variety depending on the kind of the activating agent to be used. However, in many cases, the activating agent/the specified transition metal compound is in the range of generally from 0.005/1 to 10/1, and preferably from 0.05/1 to 3.0/1, in terms of molar ratio.
The average molecular weight of the resin (AI) obtained by the ring-opening (co)polymerization in the method (a) can be adjusted by changing the reaction conditions such as the kind and concentration of the metathesis catalyst, the polymerization temperature, the kind and amount of a solvent, and the concentration of a monomer. However, it is preferred that the average molecular weight is adjusted by adding a suitable molecular weight modifier in a suitable amount to the reaction system.
Said molecular weight modifier includes, for example, xcex1-olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene and 1-decene; xcex1,xcfx89-diolefins such as 1,3-butadiene and 1,4-pentadiene; vinyl aromatic compounds such as styrene and xcex1-methylstyrene; acetylenes; and polar allyl compounds such as allyl chloride, allyl acetate and trimethylallyloxysilane.
These molecular weight modifiers can be used singly or in a combination of two or more thereof.
The amount of the molecular weight modifier used is generally 0.005 to 2 moles, preferably 0.02 to 1.0 mole, and more preferably 0.03 to 0.7 mole, per mole of the whole monomer.
Further, the solvent used in the method (a) includes, for example, alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane and n-decane; cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin and norbornane; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene and cumene; halogenated hydrocarbons such as chlorobutane, bromohexane, dichloroethane, hexamethylene dibromide and chlorobenzene; and saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate and methyl propionate.
These solvents can be used singly or in a combination of two or more thereof.
The radical copolymerization in the method (b) can be carried out, for example, using a radical polymerization catalyst, such as hydroperoxides, dialkylperoxides, diacylperoxides and azo compounds, in a suitable solvent.
The solvent used in the method (b) includes, for example, those exemplified in said method (a) and, in addition thereto, tetrahydrofuran and the like. These solvents can be used singly or in a combination of two or more thereof.
The degree of hydrolysis in said method (c) generally ranges from 10 to 100 mole %, preferably 20 to 95 mole %.
The degree of introduction of the acid-cleavable ester group according to said method (d) generally ranges from 10 to 70 mole %, preferably 20 to 60 mole %.
In the method (e), the halogen atom, the monovalent hydrocarbon group having 1 to 10 carbon atoms, and the monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms, of C and D in the general formula (8) include, for example, the same groups as those exemplified for said general formula (1) and general formula (2).
The norbornene derivatives (b) include the compounds exemplified for said norbornene derivatives (a) in which the ester group therein has been converted into a carboxyl group or a hydroxyl group.
In the present invention, when two or more of said norbornene derivatives (b) are mixed for use, it is also preferred that the compound represented by the general formula (8) where n is 0 and the compound represented by the same formula where n is 1 are used in combination.
The (co)polymer used in the method (e) can be obtained by hydrolyzing the resin (AI) obtained by said method (a) or (b), or may be synthesized by another method.
The degree of introduction of the acid-cleavable ester group according to said method (e) generally ranges from 10 to 70 mole %, preferably 20 to 60 mole %.
In said method (f), the other acid-cleavable group includes, for example, a linear acetal group such as methoxymethyloxy, ethoxymethyloxy, n-propoxymethyloxy, isopropoxymethyloxy, n-butoxymethyloxy, t-butoxymethyloxy, phenoxymethyloxy and trichloroethoxymethyloxy groups; a cyclic acetal group such as tetrahydrofuranyloxy and tetrahydropyranyloxy; a carbonate group such as isopropoxycarbonyloxy, 2-butenyloxycarbonyloxy, t-butoxycarbonyloxy, l-methyl-2-propenyloxycarbonyloxy, cyclohexyloxycarbonyloxy and 2-cyclohexenyloxycarbonyloxy groups; an orthocarbonate group such as trimethoxymethyloxy, triethoxymethyloxy, tri-n-propoxymethyloxy and methoxydiethoxymethyloxy; a (cyclo)alkyl ether such as methyl ether, ethyl ether, n-propyl ether, isopropyl ether, n-butyl ether, 2-methylpropyl ether, 1-methylpropyl ether, t-butyl ether, cyclohexyl ether and t-butylcyclohexyl ether groups; an alkenyl ether such as allyl ether, 2-butenyl ether, 2-cyclohexenyl ether and 1-methyl-2-propenyl ether groups; an aralkyl ether such as benzyl ether and t-butyl benzyl ether groups; and an enol ether such as vinyl ether, 1-propenyl ether, 1-butenyl ether, 1,3-butadienyl ether and phenylvinyl ether.
Examples of the introduction reaction of the other acid-cleavable group according to the method (f) include the following:
(f-1) an esterification reaction based on the addition reaction of the carboxyl group contained in each resin with 2,3-dihydro-4H-pyran,
(f-2) an etherification reaction based on the addition reaction of the hydroxyl group contained in each resin with 2,3-dihydro-4H-pyran, and
(f-3) an esterification reaction based on the reaction of the hydroxyl group contained in each resin with a dialkyl dicarbonate.
The degree of introduction of the other acid-cleavable group according to said method (f) generally ranges from 10 to 70 mole %, preferably 20 to 60 mole %.
The resin (A) in the present invention preferably contains a small amount of carbon-carbon unsaturated bonding from the viewpoint of transparency to radiation. The resin (A) like this can be obtained, for example, by effecting addition reaction such as hydrogenation, hydration, addition of a halogen, or addition of a hydrogen halide either in a suitable step in the ring-opening (co)polymerization method according to said method (a) or said method (e), or after the method (a) or (e). Particularly, the resin (AI) obtained by effecting hydrogenation reaction is preferred. The resin (AI) obtained by said method (b) or the radical (co)polymerization method according to said method (e) has substantially no carbon-carbon unsaturated bonding.
The degree of hydrogenation in the hydrogenated resin (AI) is preferably 70% or more, more preferably 90% or more, and particularly preferably 100%.
The catalysts used in said hydrogenation reaction include those which have been used in the conventional hydrogenation reaction of olefinic compounds.
Among these hydrogenation catalysts, heterogeneous catalysts include, for example, a solid catalyst comprising a noble metal, such as Pd, Pt, Ni, Rh and Ru, supported on a carrier, such as carbon, silica, alumina and titania. These heterogeneous catalysts can be used singly or in combination of two or more thereof.
On the other hand, homogeneous catalysts include a nickel naphthenenate/triethylaluminum system, a nickel acetylacetonate/triethylaluminum system, a cobalt octenoate/n-butyllithium system, a titanocene dichloride/diethylaluminum monochloride system, and a rhodium system such as rhodium acetate and chlorotris(triphenylphosphine)rhodium. These homogeneous catalysts can be used singly or in combination of two or more thereof.
Among said hydrogenation catalysts, the heterogeneous catalysts are preferred from the viewpoint of their high reaction activity, their easy removal after the reaction, and a superior color tone of the resulting resin (AI).
The hydrogenation reaction can be carried out at generally 0 to 200xc2x0 C., and preferably 20 to 180xc2x0 C., in a hydrogen gas atomosphere having generally normal pressure to 300 atm, and preferably 3 to 200 atm.
Preferable resin (AI) in the present invention includes particularly the following resin (AII), resin (AIII) and resin (AIV).
The resin (AII) is a resin comprising a structural unit represented by the following general formula (3): 
wherein in the general formula (3), n is 0 or 1, A represents a hydrogen atom, a halogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms or a monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms, and X represents an acid-cleavable group.
In the general formula (3), the halogen atom, the monovalent hydrocarbon group having 1 to 10 carbon atoms or the monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms of A, and the acid-cleavable group of X include, for example, the same groups as those exemplified for said general formula (1) and general formula (2).
The resin (AII) preferably contains as the acid-cleavable group of X the group xe2x80x94(CH2)iCOOR1 described as the acid-cleavable group in the general formula (1) and general formula (2), more preferably contains as the acid-cleavable group of X the group xe2x80x94COOR1, and particularly preferably contains as the acid-cleavable group of X a (cyclo)alkoxycarbonyl group such as methoxycarbonyl, ethoxycarbonyl, n-propoxycarbonyl, isopropoxycarbonyl, n-butoxycarbonyl, 2-methylpropoxycarbonyl, 1-methylpropoxycarbonyl, t-butoxycarbonyl, n-pentyloxycarbonyl, n-hexyloxycarbonyl, n-heptyloxycarbonyl, n-octyloxycarbonyl, n-decyloxycarbonyl, cyclopentyloxycarbonyl, cyclohexyloxycarbonyl, 4-t-butylcyclohexyloxycarbonyl, cycloheptyloxycarbonyl and cyclooctyloxycarbonyl groups; an aryloxycarbonyl group such as phenoxycarbonyl, 4-t-butylphenoxycarbonyl and 1-naphthyloxycarbonyl groups; and an aralkyloxycarbonyl group such as benzyloxycarbonyl and 4-t-butylbenzyloxycarbonyl.
A more specific typical example of the structural unit of the general formula (3) is represented by the formula (3-1): 
wherein n is 0 or 1, and R1 is as defined above.
In said resin (AII), one or more structural units represented by the general formula (3) can be present.
The resin (AIII) is a random copolymer comprising a structural unit represented by the following general formula (3) and a structural unit represented by the following general formula (4). 
wherein in the general formula (3) and general formula (4), n and m are independently 0 or 1, A and B represent independently a hydrogen atom, a halogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms or a monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms, and X represents an acid-cleavable group.
In the general formula (3) and general formula (4), the halogen atom, the monovalent hydrocarbon group having 1 to 10 carbon atoms or the monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms of A and B, and the acid-cleavable group of X include, for example, the same groups as those exemplified for said general formula (1) and general formula (2).
The resin (AIII) preferably contains as the acid-cleavable group of X the group xe2x80x94(CH2)iCOOR1 described as the acid-cleavable group in the general formula (1) and general formula (2), more preferably contains as the acid-cleavable group of X the group xe2x80x94COOR1, and particularly preferably contains as the acid-cleavable group of X a (cyclo)alkoxycarbonyl group such as methoxycarbonyl, ethoxycarbonyl, n-propoxycarbonyl, isopropoxycarbonyl, n-butoxycarbonyl, 2-methylpropoxycarbonyl, 1-methylpropoxycarbonyl, t-butoxycarbonyl, n-pentyloxycarbonyl, n-hexyloxycarbonyl, n-heptyloxycarbonyl, n-octyloxycarbonyl, n-decyloxycarbonyl, cyclopentyloxycarbonyl, cyclohexyloxycarbonyl, 4-t-butylcyclohexyloxycarbonyl, cycloheptyloxycarbonyl and cyclooctyloxycarbonyl groups; an aryloxycarbonyl group such as phenoxycarbonyl, 4-t-butylphenoxycarbonyl and 1-naphthyloxycarbonyl groups; and an aralkyloxycarbonyl group such as benzyloxycarbonyl and 4-t-butylbenzyloxycarbonyl.
A more specific typical example of the resin (AIII) is comprised of a structural unit of the formula (3-1) above and a structural represented by the formula (4-1):
[Chemical 49]
wherein m is 0 or 1.
The molar ratio of the structural unit represented by the general formula (3) to the structural unit represented by the general formula (4) in the resin (AIII) is generally 20/80 to 95/5, and preferably 30/70 to 90/10.
In the resin (AIII), there can be present one or more structural units represented by the general formula (3) and one or more structural units represented by the general formula (4).
The resin (AIV) is a random copolymer containing a structural unit represented by the following general formula (5) and a structural unit represented by the following general formula (6). 
wherein in the general formula (5) and general formula (6), A and B represent independently a hydrogen atom, a halogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms or a monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms, and X and Y represent independently a hydrogen atom, a halogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, a monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms or an acid-cleavable group, provided that at least one of X and Y is an acid-cleavable group.
In the general formula (5) and general formula (6), the halogen atom, the monovalent hydrocarbon group having 1 to 10 carbon atoms or the monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms of A, B, X and Y, and the acid-cleavable group of X and Y include, for example, the same groups as those exemplified for said general formula (1) and general formula (2).
The resin (AIV) preferably contains as the acid-cleavable group of X and Y the group xe2x80x94(CH2)iCOOR1 described as the acid-cleavable group in the general formula (1) and general formula (2), more preferably contains as the acid-cleavable group of X and Y the group xe2x80x94COOR1, and particularly preferably contains as the acid-cleavable group of X and Y a (cyclo)alkoxycarbonyl group such as methoxycarbonyl, ethoxycarbonyl, n-propoxycarbonyl, isopropoxycarbonyl, n-butoxycarbonyl, 2-methylpropoxycarbonyl, 1-methylpropoxycarbonyl, t-butoxycarbonyl, n-pentyloxycarbonyl, n-hexyloxycarbonyl, n-heptyloxycarbonyl, n-octyloxycarbonyl, n-decyloxycarbonyl, cyclopentyloxycarbonyl, cyclohexyloxycarbonyl, 4-t-butylcyclohexyloxycarbonyl, cycloheptyloxycarbonyl and cyclooctyloxycarbonyl groups; an aryloxycarbonyl group such as phenoxycarbonyl, 4-t-butylphenoxycarbonyl and 1-naphthyloxycarbonyl groups; and an aralkyloxycarbonyl group such as benzyloxycarbonyl and 4-t-butylbenzyloxycarbonyl.
A more specific typical example of the resin (AIV) is comprised of a structural unit of the formula (5-1) and a structural represented by the formula (6-1): 
wherein in the general formula (5-1) and general formula (6-1), R1 is independently as defined above.
The molar ratio of the structural unit represented by the general formula (5) to the structural unit represented by the general formula (6) in the resin (AIV) is generally 5/95 to 95/5, and preferably 10/90 to 90/10.
In the resin (AIV), there can be present one or more structural units represented by the general formula (5) and one or more structural units represented by the general formula (6).
The resin (A) in the present invention has a weight average molecular weight in terms of polystyrene, measured by gel permeation chromatography (GPC) (hereinafter referred to as xe2x80x9cMwxe2x80x9d) of generally 5,000 to 300,000, preferably 5,000 to 200,000, and more preferably 10,000 to 100,000. If the Mw of the resin is less than 5,000, heat resistance as a photoresist may tend to lower. If the Mw is more than 300,000, developability as a photoresist may tend to lower.
The resin (A) in the present invention has a glass transition temperature in the range of preferably 80 to 180xc2x0 C., and more preferably 90 to 170xc2x0 C. The glass transition temperature of the resin (A) being in the range of 80 to 180xc2x0 C. results in obtaining a radiation-sensitive resin composition particularly excellent in heat resistance, sensitivity, etc. as a photoresist.
In the present invention, the resin (A) can be used singly or in combination of two or more thereof.
Further, it is preferred that the resin (A), preferably the resin (AI), and particularly preferably the resin (AII), resin (AIII) and resin (AIV), in the present invention contains impurities in an amount as small as possible. The impurities result mainly from a catalyst used in the production of the resins. Examples of the impurities to be considered particularly from the view point of a photoresist include halogens such as fluorine, chlorine and bromine, and the metals of Group IV, V, VI, VII and VIII in the Deming""s periodic table.
It is preferred that the amount of the residual halogen contained in the resin is 3 ppm or less, particularly 2 ppm or less, and that the amount of the residual metal contained is 300 ppb or less, particularly 100 ppb or less. Furthermore, it is preferred that the amount of the residual halogen contained is 3 ppm or less, particularly 2 ppm or less, and that the amount of the residual metal contained is 300 ppb or less, particularly 100 ppb or less. The control of the amounts of the impurities contained to said values or less results in a further improvement in yield when a semiconductor is produced using the radiation-sensitive resin composition of the present invention as well as in sensitivity, resolution and process-stability, as a photoresist.
Methods for reducing the impurities contained in the resin, in the case of the residual halogen, include methods, for example, (a) washing or liquid-liquid extraction of a resin solution with pure water, (b) a combination of washing or liquid-liquid extraction of a resin solution with pure water, and a physical purification process such as ultrafiltration or centrifugal separation, (c) a method using an alkaline aqueous solution or an acidic aqueous solution instead of pure water in the above methods. In case of the residual metal, in addition to the same methods as said methods (a) to (c), (d) a method treating a resin by oxidation, reduction, exchange of ligand, exchange of ion pair or the like to remarkably increase solubility of the residual metal contained in the resin in a solvent or in water, followed by treating according to said methods (a) to (c).
The treatment for reducing the impurities can be carried out in any step after the polymerization step for producing the resin.
(B) Acid-generating Agent
The radiation-sensitive acid-generating agent (hereinafter, referred to as xe2x80x9cacid-generating agent (B)xe2x80x9d) generating an acid upon irradiation with radiation (hereinafter, referred to as xe2x80x9cexposurexe2x80x9d) used in the present invention has a function of cleaving an acid-cleavable group present in the resin (A) and/or an acid-cleavable additive as described later by the action of an acid generated by the exposure, whereby the exposed portion of a photoresist film become readily soluble in an alkaline developing solution and a positive photoresist pattern is formed.
The acid-generating agent (B) includes {circle around (1)} onium salts, {circle around (2)} halongen-containing compounds, {circle around (3)} diazoketone compounds, {circle around (4)} sulfone compounds, and {circle around (5)} sulfonic acid compounds.
Examples of these acid-generating agents (B) include the following.
{circle around (1)} Onium Salts:
Onium salts include, for example, iodonium salts, sulfonium salts, phosphonium salts, diazonium salts and pyridinium salts.
Specific examples of preferable onium salts include diphenyliodonium triflate, diphenyliodonium pyrenesulfonate, diphenyliodonium dodecylbenzenesulfonate, bis(4-t-butylphenyl)iodonium triflate, bis(4-t-butylphenyl)iodonium dodecylbenzenesulfonate, bis(4-t-butylphenyl)iodonium naphthalenesulfonate, bis(4-t-butylphenyl)iodonium hexafluoroantimonate, triphenylsulfonium triflate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium naphthalenesulfonate, (hydroxyphenyl)benzenemethylsulfonium toluenesulfonate, 1-(naphthylacetomethyl)tetrahydro-thiophenium triflate, cyclohexylmethyl(2-oxocyclohexyl)sulfonium triflate, dicyclohexyl(2-oxocyclohexyl)sulfonium triflate, dimethyl(2-oxocyclohexyl)sulfonium triflate, dimethyl(4-hydroxynaphthyl)sulfonium triflate, dimethyl(4-hydroxynaphthyl)sulfonium tosylate, dimethyl(4-hydroxynaphthyl)sulfonium dodecylbenzenesulfonate, dimethyl(4-hydroxynaphthyl)sulfonium naphthalenesulfonate, diphenyliodonium hexafluoroantimonate, triphenylsulfonium camphorsulfonate and (4-hydroxyphenyl)benzylmethylsulfonium toluenesulfonate.
{circle around (2)} Halongen-containing Compounds:
Halogen-containing compounds include, for example, haloalkyl group-containing hydrocarbon compounds and haloalkyl group-containing heterocyclic compounds.
Specific examples of preferable halogen-containing compounds include (trichloromethyl)-s-triazine derivatives such as phenyl-bis(trichloromethyl)-s-triazine, methoxyphenyl-bis(trichloromethyl)-s-triazine and naphthyl-bis(trichloromethyl)-s-triazine; and 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane.
{circle around (3)} Diazoketone Compounds:
Diazoketone compounds include, for example, 1,3-diketo-2-diazo compounds, diazobenzoquinone compounds and diazonaphthoquinone compounds.
Specific examples of preferable diazoketones include 1,2-naphthoquinonediazide-4-sulfonylchloride, 1,2-naphthoquinonediazide-5-sulfonylchloride, 1,2-naphthoquinonediazide-4-sulfonic acid ester or 1,2-naphthoquinonediazide-5-sulfonic acid ester of 2,3,4,4xe2x80x2-tetrahydrobenzophenone, and 1,2-naphthoquinonediazide-4-sulfonic acid ester or 1,2-naphthoquinonediazide-5-sulfonic acid ester of 1,1,1-tris(hydroxyphenyl)ethane.
{circle around (4)} Sulfone Compounds:
Sulfone compounds include, for example, xcex2-ketosulfones, xcex2-sulfonylsulfones, and their xcex1-diazo compounds.
Specific examples of preferable sulfone compounds include 4-trisphenacyl sulfone, mesityl phenacyl sulfone and bis(phenylsulfonyl)methane.
{circle around (5)} Sulfonic Acid Compounds:
Sulfonic acid compounds include, for example, alkylsulfonic acid esters, alkylsulfonic acid imides, haloalkylsulfonic acid esters, arylsulfonic acid esters and iminosulfonates.
Specific examples of preferable sulfonic acid compounds include benzoin tosylate, triflate of pyrogallol, nitrobenzyl-9,10-diethoxyanthracene-2-sulfonate, trifluoromethanesulfonylbicyclo[2.2.1]hept-5-ene-2,3-dicarbodiimide, N-hydroxysuccinimide triflate and 1,8-naphthalenedicarboxylic acid imide triflate.
Among these acid-generating agents (B), particularly preferred are diphenyliodonium triflate, bis(4-t-butylphenyl)iodonium triflate, triphenylsulfonium triflate, cyclohexylmethyl(2-oxocyclohexyl)sulfonium triflate, dicyclohexyl(2-oxocyclohexyl)sulfonium triflate, dimethyl(2-oxocyclohexyl)sulfonium triflate, 1-(naphthylacetomethyl)tetrahydro-thiophenium triflate, 4-hydroxynaphthyl)dimethylsulfonium triflate, dimethyl(4-hydroxynaphthyl)sulfonium triflate, trifluoromethanesulfonylbicyclo[2.2.1]hept-5-ene-2,3-dicarbodiimide, N-hydroxysuccinimide triflate and 1,8-naphthalenedicarboxylic acid imide triflate.
In the present invention, the acid-generating agent (B) can be used singly or in combination of two or more thereof.
The amount of the acid-generating agent (B) used is generally 0.1 to 10 parts by weight, preferably 0.5 to 7 parts by weight, per 100 parts by weight of the resin (A), from the viewpoint of ensuring sensitivity and developability as a photoresist. If the amount of the acid-generating agent (B) used is less than 0.1 part by weight, sensitivity and developability may be lowered. If the amount is more than 10 parts by weight, transparency for radiation is lowered and, as a result, it may show a tendency to obtain a rectangular photoresist pattern with difficulty.
In the case where the resin (A) contains an acid-cleavable group like the resin (AI), resin (AII), resin (AIII) and resin (AIV), the addition of a compound having a group which is cleavable by the action of an acid to increase affinity of the resin for an alkaline developing solution (hereinafter, referred to as xe2x80x9cacid-cleavable additivexe2x80x9d) can further improve contrast as a chemically amplified positive type photoresist. In the case where the resin (A) used in a radiation-sensitive resin composition contains no acid-cleavable group, it is necessary to add an acid cleavable additive to the composition so that the composition can be used as a chemically amplified positive type photoresist.
The acid-cleavable additive includes, for example, polymeric compounds or low-molecular weight compounds having at least one acid-cleavable group such as, for example, hydroxyl group and/or carboxyl group protected with t-butyl group, hydroxyl group and/or carboxyl group protected with tetrahydropyranyl group, carboxyl group protected with 3-oxocyclohexyl group, carboxyl group protected with isobornyl group, hydroxyl group protected with t-butoxycarbonyl group, and the like.
The polymeric compounds out of the acid-cleavable additives include, for example, polymers and copolymers containing at least one repeated unit selected from the group consisting of t-butyl (meth)acrylate unit, tetrahydropyranyl (meth)acrylate unit, 3-oxocyclohexyl (meth)acrylate unit and isobornyl (meth)acrylate unit.
Specific examples of the polymeric compounds include t-butyl (meth)acrylate homopolymers, t-butyl (meth)acrylate/methyl (meth)acrylate copolymers, t-butyl (meth)acrylate/(meth)acrylic acid copolymers, t-butyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid copolymers, t-butyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/adamantyl (meth)acrylate copolymers, t-butyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/adamantylmethyl (meth)acrylate copolymers, t-butyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/tetracyclodekanyl (meth)acrylate copolymers, t-butyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/tetrahydropyranyl (meth)acrylate copolymers, t-butyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/3-oxocyclohexyl (meth)acrylate copolymers, t-butyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/isobornyl (meth)acrylate copolymers; tetrahydropyranyl (meth)acrylate homopolymers, tetrahydropyranyl (meth)acrylate/methyl (meth)acrylate copolymers, tetrahydropyranyl (meth)acrylate/(meth)acrylic acid copolymers, tetrahydropyranyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid copolymers, tetrahydropyranyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/adamantyl (meth)acrylate copolymers, tetrahydropyranyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/adamantylmethyl (meth)acrylate copolymers, tetrahydropyranyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/tetracyclodecanyl (meth)acrylate copoymers, tetrahydropyranyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/t-butyl (meth)acrylate copolymers, tetrahydropyranyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/3-oxocyclohexyl (meth)acrylate copolymers, tetrahydropyranyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/isobornyl (meth)acrylate copolymers; 3-oxocyclohexyl (meth)acrylate homopolymers, 3-oxocyclohexyl (meth)acrylate/methyl (meth)acrylate copolymers, 3-oxacyclohexyl (meth)acrylate/(meth)acrylic acid copolymers, 3-oxocyclohexyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid copolymers, 3-oxocyclohexyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/adamantyl (meth)acrylate copolymers, 3-oxocyclohexyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/adamantylmethyl (meth)acrylate copolymers, 3-oxocyclohexyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/tetracyclodecanyl (meth)acrylate copoymers, 3-oxocyclohexyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/t-butyl (meth)acrylate copolymers, 3-oxocyclohexyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/tetrahydropyranyl (meth)acrylate copolymers, 3-oxocyclohexyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/isobornyl (meth)acrylate copolymers; isobornyl (meth)acrylate homopolymers, isobornyl (meth)acrylate/methyl (meth)acrylate copolymers, isobornyl (meth)acrylate/(meth)acrylic acid copolymers, isobornyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid copolymers, isobornyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/adamantyl (meth)acrylate copolymers, isobornyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/adamantylmethyl (meth)acrylate copolymers, isobornyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/tetracyclodecanyl (meth)acrylate copolymers, isobornyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/t-butyl (meth)acrylate copolymers, isobornyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/tetrahydropyranyl (meth)acrylate copolymers, isobornyl (meth)acrylate/methyl (meth)acrylate/(meth)acrylic acid/3-oxocyclohexyl (meth)acrylate copolymers; and the like.
These polymeric compounds can be used singly or as a mixture of two or more.
Specific examples of the low-molecular weight compounds out of the acid-cleavable additives include t-butyl adamantane-carboxylate, tetrahydropyranyl adamantane-carboxylate, 3-oxocyclohexyl adamantane-carboxylate, t-butyl adamantyl acetate, tetrahydropyranyl adamantyl acetate, 3-oxocyclohexyl adamantyl acetate; t-butyl 1-naphtylacetate, tetrahydropyranyl 1-naphthylacetate, 3-oxocyclohexyl 1-naphthylacetate, t-butyl 2-naphthylacetate, tetrahydropyranyl 2-naphthylacetate, 3-oxocyclohexyl 2-naphthylacetate, 1-naphthoic acid t-butyl ester, 1-naphthoic acid tetrahydropyranyl ester, 1-naphthoic acid 3-oxocyclohexyl ester, 2-naphthoic acid t-butyl ester, 2-naphthoic acid tetrahydropyranyl ester, 2-naphthoic acid 3-oxocyclohexyl ester; cholic acid t-butyl ester, cholic acid tetrahydropyranyl ester, cholic acid 3-oxocyclohexyl ester; 1-t-butoxycarbonyloxynaphthalene, 2-t-butoxycarbonyloxynaphthalene, 1,5-bis(t-butoxycarbonyloxy)naphthalene, 1-carbo-t-butoxymethoxynaphthalene, 2-carbo-t-butoxymethoxynaphthalene, 1,5-bis(carbo-t-butoxymethoxy)naphthalene, and the like.
These low-molecular weight compounds can be used singly or as a mixture of two or more.
In the present invention, the polymeric compound and the low-molecular weight compound may be used in combination as the acid-cleavable additive.
The amount of the acid-cleavable additive to be added is normally 200 parts by weight or less, preferably 5 to 150 parts by weight, per 100 parts by weight of the resin (A). If the amount of the acid-cleavable additive exceeds 200 parts by weight, adhesion to a substrate may show a tendency to drop.
In the positive type radiation-sensitive resin composition of the present invention, the addition of a compound which acts as a Lewis base to an acid generated from the acid-generating agent (B) (hereinafter, referred to as xe2x80x9cLewis base additivexe2x80x9d) can improve perpendicularity of the side walls of a photoresist patter in section more effectively.
The Lewis base additive includes, for example, nitrogen-containing basic compounds and salts thereof, carboxylic acids, alcohols, etc. Preferred are the nitrogen-containing basic compounds.
Specific examples of the nitrogen-containing basic compounds include amine compounds such as triethylamine, tri n-propylamine, triisopropylamine, tri n-butylamine, tri n-hexyl amine, triethanolamine, triphenylamine, aniline, N,N-dimethylaniline, 2-methylaniline, 3-methylaniline, 4-methylaniline, 4-nitroaniline, 1-naphthylamine, 2-naphthylamine, diphenylamine, ethylenediamine, tetramethylenediamine, hexamethylenediamine, pyrrolidine, piperidine, etc.; imidazole compounds such as imidazole, 4-methylimidazole, 4-methyl-2-phenylimidazole, thiabendazole, etc.; pyridine compounds such as pyridine, 2-methylpyridine, 4-ethylpyridine, 2-hydroxypyridine, 4-hydroxypyridine, 2-phenylpyridine, 4-phenylpyridine, nicotinic acid, nicotinic acid amide, quinoline, acridine, etc.; and other nitrogen-containing heterocyclic compounds such as purine, 1,3,5-triazine, triphenyl-1,3,5-triazine, 1,2,3-triazole, 1,2,4-triazole, and urazol.
These nitrogen-containing basic compounds can be used singly or as a mixture of two or more.
The amount of the Lewis base additive to be added is normally 1 mol or less, preferably 0.05 to 1 mole, per mole of the acid-generating agent (B). If the amount of the Lewis base additive exceeds 1 mole, sensitivity as a photoresist of the radiation-sensitive composition may show a tendency to drop.
To the radiation-sensitive resin composition of the present invention can be added optionally a variety of other additives.
The additives include, for example, surface-active agents acting to improve coating properties, developability, and so forth.
The surface-active agents include, for example, nonionic surface active agents such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyethylene glycol dilaurate, and polyethylene glycol distearate, and the products available under the tradenames of KP341 (products of Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75 and No. 95 (products of Kyoei-Sha Yushi Kagaku Kogyo K.K.), F-Top EF301, EF303 and EF352 (products of To-chem Products K.K.), Megafacs F171 and F173 (products of Dainippon Ink and Chemicals, Inc.), Fluorad FC430 and FC431 (products of Sumitomo 3M Co., Ltd.), and Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105 and SC-106 (products of Asahi Glass Co., Ltd.).
These surface-active agents can be used singly or as a mixture of two or more.
The amount of the surface active agent to be added is normally 2 parts by weight or less per 100 parts by weight of the total of the resin (A), the acid-generating agent (B, and the acid-cleavable additive.
Additives other than those described above include a halation preventive agent, adhesion aid, stabilizer, defoaming agent, etc.
The radiation-sensitive resin composition according to the present invention contains as essential components the resin (A) and the acid-generating agent (B), and optionally may contain the acid-cleavable additive, Lewis base additive, or other additives. The composition is useful as, particularly, a chemically amplified positive type photoresist.
In said chemically amplified positive type photoresist, the acid-generating agent (B) generates an acid upon exposure to radiation to produce an acid, and by the action of the acid the acid-cleavable group contained in the resin (A) and/or the acid-cleavable additive undergoes, for example:
(q) a reaction in which an alkoxycarbonyl group cleaves to be converted into an carboxyl group,
(h) a reaction in which an alkylcarbonyloxy group cleaves to be converted into a hydroxyl group,
(i) a reaction in which a cyano group cleaves to be converted into an carboxyl group,
(j) a reaction in which an acid anhydride group cleaves to be converted into carboxyl groups, or the like, so that the exposed portions of the photoresist become readily soluble in an alkaline developing solution and are dissolved by the alkaline developing solution and removed away to give a photoresist pattern of positive type.
The radiation-sensitive resin composition according to the present invention is prepared as a composition solution before use by dissolving the components in a solvent so that the content of all the solid components may become, for example, 5 to 50% by weight and then normally filtering the resulting solution with a filter having a pore diameter of about 0.2 xcexcm .
Solvents which can be used for preparation of said composition solution include, for example, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, t-butyl alcohol, cyclohexanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-propyl ether, diethylene glycol di-n-butyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-propyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol mono-n-propyl ether acetate, toluene, xylene, methyl ethyl ketone, methyl n-propyl ketone, isopropyl ketone, methyl n-butyl ketone, methyl isobutyl ketone, 2-heptanone, 3-heptanone, 4-heptanone, cyclopentanone, cyclohexanone, methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutyrate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutyl propionate, 3-methyl-3-methoxybutyl butyrate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl acetoacetate, ethyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, benzyl ethyl ether, dihexyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, acetonylacetone, isophorone, capric acid, caprylic acid, 1-octanol, 1-nonanol, benzyl alcohol, benzyl acetate, ethyl benzoate, diethyl oxalate, diethyl maleate, y-butyrolactone, ethylene carbonate, propylene carbonate, and so forth.
These solvents can be used singly or as a mixture of two or more.
To form a photoresist pattern from the radiation-sensitive resin composition of the present invention, the composition solution prepared as described above is applied to a substrate such as, for example, a silicon wafer, a wafer covered with aluminum or the like by a suitable coating method such as spin coating, flow-coating, roll coating or the like, to form a photoresist film, which is then optionally pre-baked, and thereafter the photoresist film is subjected to exposure so that a prescribed photoresist pattern may be formed. As radiation used in exposure, can be used a variety of radiations, e.g., far ultra-violet radiation such as KrF excimer laser (wave length: 248 nm) or ArF excimer laser (wave length: 193 nm), X ray such as synchrotron radiation, charged particle radiation such as electron beam, etc. Particularly, KrF excimer laser or ArF excimer laser is preferred, and ArF excimer laser is more preferred.
In the present invention, it is preferred to carry out heating treatment after the exposure (hereinafter, referred to as xe2x80x9cpost-exposure bakingxe2x80x9d). The post-exposure baking enables the reactions of (g)-(j) described above to proceed smoothly. Although the conditions of heating at the post-exposure baking vary depending on the formulation of a composition, heating is conducted normally at 30 to 200xc2x0 C., preferably at 50 to 170xc2x0 C.
To develop potential performance of the radiation-sensitive resin composition of the present invention it is possible to form an organic or inorganic anti-reflective coating on a substrate as disclosed in, for example, Japanese Patent Publication (kokoku) No. 6-12452, or to form a protective coating on a photoresist film for the purpose of preventing influence by basic impurities or the like contained in the environmental atmosphere as disclosed in, for example, Japanese Laid-open Patent Publication (kokai) No.5-188598, or to combine these techniques.
Subsequently, the exposed photoresist film is developed, and a prescribed photoresist pattern is thereby formed.
When the radiation-sensitive resin composition of the present invention is used as a chemically amplified positive type photoresist, developing solutions which are preferably used include, for example, alkaline aqueous solutions containing at least one alkaline compound such as, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, demethylamine, triethanolamine, tetramethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo[5.4.0]-7-undecene, 1,5-diazabicyclo[4.3.0]-5-nonene or the like. The alkaline aqueous solutions normally have a concentration of 10% by weight or less. If the concentration exceeds 10% by weight, unexposed portions are also dissolved unfavorably.
To the developing solution of the alkaline aqueous solution, for example, an organic solvent can be added.
Specific examples of the organic solvent include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, 3-methyl-2-cyclopentanone, 2,6-dimethylcyclohexanone and the like; alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, t-butyl alcohol, cyclopentanol, cyclohexanol, 1,4-hexanediol, 1,4-hexanedimethylol, and the like; ethers such as tetrahydrofuran, dioxanes and the like; esters such as ethyl acetate, butyl acetate, isoamyl acetate and the like; aromatic hydrocarbons such as toluene, xylene and the like; and phenol, acetonylacetone, and dimethylformamide.
These organic solvents can be singly or as a mixture of two or more.
The amount of an organic solvent is preferably 100% by volume or less with respect to the alkaline aqueous solution. If the amount of the organic solvent exceeds 100% by volume, unfavorably developability is lowered and serious undeveloped residue is produced at developed portions.
To the developing solution of an alkaline aqueous solution can be added a surface active agent or the like in a proper amount.
Development with a developing solution of an alkaline aqueous solution is normally followed by washing with water and drying.